THE MEDITERRANEAN FRUIT FLY. 
39 
PARASITES. 
The very climatic and host conditions that have made the Medi- 
terranean fruit fly an unusually serious pest in Hawaii and that, 
with crop conditions as they are, have made artificial methods of 
control impracticable, have been most favorable for an attempt 
at control by means of parasites. An abundance of the fruit fly upon 
which to feed and a climate permitting increase each month in the 
year have made conditions ideal. The search for and discovery of 
parasites, and their introduction and establishment where previously 
there had been none, has been one of the entomological romances of 
the present time. The 
parasites now at work 
killing the fruit fly in 
Hawaii have been in- 
troduced by the Ha- 
waiian Board of Agri- 
culture and Forestry as 
a result of the Silvestri 
and the Fullaway- 
Bridwell expeditions 
to Africa. 
These two expedi- 
tions resulted in the 
establishment in the 
islands between May, 
1913, and October, 
1914, of four promis- 
ing parasites : one from 
South Africa, 1 one 
from eastern Austra- 
lia, 2 and two from 
Nigeria, 3 West Africa. 
Of these, only one, the 
South African Opius, 
was discovered as a 
parasite of the Mediterranean fruit fly. The three others were found 
parasitizing other fruit flies, and they have adapted themselves 
in Hawaii to the Mediterranean fruit fly. None of them, however, 
has been known to attack the melon fly in the gardens in 
Hawaii. Large numbers of all the parasites have been reared and 
have been liberated in all parts of the islands, until to-day they are 
well able to care for themselves. They have multiplied with 
remarkable rapidity and have unquestionably reduced the numerical 
Fig. 30.— Diagrammatic drawing of a cross section of a coffee cherry 
to illustrate comparative ease with which the South African para- 
site can lay eggs in the fruit-fly larva: c, Coffee bean; b, pulp 
destroyed by maggot; c, skin of cherry; d, maggot of fruit fly; e, 
parasite forcing its stinger through skin of cherry into maggot. 
(Original.) 
Opius humilis Silv. 2 Diachasma tryoni Cam. 3 D.fullawayi Silv. and Tetrastichus giffardianus Silv. 
